The security of data communications networks is become increasingly important. As more and more sensitive data is transmitted over such networks, it is very important that data belonging to one user on the network does not somehow become exposed or visible to another user on the network. In addition, as organisations place ever greater reliance on the availability of networks for conducting their business and other operations, a network must be robust against hardware and software errors, component down-time, abnormal traffic conditions, and so on.
Some network problems may be innocent (i.e. non-malicious) in origin. For example, they may be caused by a hardware failure, a software bug, or some other weakness. In other cases, an adversary may try to cause network problems deliberately with malicious intent, such as for motives of terrorism, commercial gain, political persuasion, etc.. Depending upon the motives of the attack, the particular objective may be to obtain inappropriate access to data communications over the network, or to induce non-availability or some other non-functioning of the network. A malicious attack may exploit a known weakness in the network, and/or the attack may attempt to generate problems by the deliberate injection of errors, anomalous traffic, and so on.
It is therefore important for a network to be reliable and secure, and to be as resistant as possible against problems, whether deliberate or otherwise. In addition, it is also important for a network to be able to operate quickly and without delays.